Column selection of a HDU

In this window, you select the columns in a table extension you want to
display. By default, all the columns in the table are selected. By
clicking on the column name, you can select and unselect individual
columns. The total number of columns and rows
are listed at the top of the window.

Copy and paste a column from one table to another

1. Select the range of values in the first table by clicking on the
first row of the column (that cell will then be highlighted) and then
move to the last row of the column, and, click on it while holding down
the 'Shift' key. The whole range should then be highlighted.

2. Copy the selected values into the clipboard, under the Edit menu (or
use the Alt-C or Crtl-C short cut.)

3. Select the first row of the column in the 2nd table, then paste the
clipboard into that column using the 'paste' item under the Edit menu,
or use the Alt-V or Ctrl-V short cut key.

This technique can also be used to copy multiple columns or rows of data
from one table to another. First click on the upper left cell to be
copied, then click on the lower right cell of the rectangular region,
while holding the 'Shift' key.